Can ATmega328PB run up to 24MHz 115200 ?

[rickygai]

I managed to run up to 22.118400MHz, but my custom bootloader built at 24MHz 115200 cannot communicate via arduino protocol.

However the pre-built version below, after uploaded, is able to communicate with bootloader via arduino protocol, but firmware cannot run properly, may be the voltage required is not up to level required, which I measured is 4.7V

C:\MiniCore\MiniCore-3.1.3\avr\bootloaders\optiboot_flash\bootloaders\atmega328pb\24000000\ optiboot_flash_atmega328pb_UART0_115200_24000000L_B5.hex

I also tested the 19200 built, but arduino protocol still fails to talk to the bootloader.

First of all, any idea why the custom compile unable to recognize the bootloader via arduino protocol ?

I am using make parameters below, any idea ?

# make atmega328pb OS=posix ENV=arduino \
AVR_FREQ=24000000UL UART=0 BAUD_RATE=115200 LED=B5 LED_START_FLASHES=2 \
CC=/c/avr-gcc/7.3.0-atmel3.6.1-arduino7/bin/avr-gcc \
OBJCOPY=/c/avr-gcc/7.3.0-atmel3.6.1-arduino7/bin/avr-objcopy \
OBJDUMP=/c/avr-gcc/7.3.0-atmel3.6.1-arduino7/bin/avr-objdump \
SIZE=/c/avr-gcc/7.3.0-atmel3.6.1-arduino7/bin/avr-size
mkdir -p bootloaders/atmega328pb/24000000UL
Using avr-gcc 7.3.0
\nUART = UART0\tLED_PIN = B5\t LED_FLASHES = 2\t SUPPORT_EEPROM = 0\t COPY_FLASH_PAGES = 0
\x1B[1m\x1B[4m
BAUD RATE CHECK: Desired: 115200 Real: 115384 UBRRL = 25 Difference: 0.1 %\x1B[0m
/c/avr-gcc/7.3.0-atmel3.6.1-arduino7/bin/avr-gcc -g -Wall -Os -fno-split-wide-types -mrelax -mmcu=atmega328pb -DF_CPU=24000000UL -DOPTIBOOT_CUSTOMVER=1 -DBAUD_RATE=115200 -DLED_START_FLASHES=2    -DLED=B5     -DUART=0 -Wl,--section-start=.text=0x7e00 -Wl,--section-start=.version=0x7ffe -Wl,--relax -nostartfiles -o bootloaders/atmega328pb/24000000UL/optiboot_flash_atmega328pb_UART0_115200_24000000UL_B5.elf optiboot_flash.o

/c/avr-gcc/7.3.0-atmel3.6.1-arduino7/bin/avr-size bootloaders/atmega328pb/24000000UL/optiboot_flash_atmega328pb_UART0_115200_24000000UL_B5.elf
   text    data     bss     dec     hex filename
    470       0       0     470     1d6 bootloaders/atmega328pb/24000000UL/optiboot_flash_atmega328pb_UART0_115200_24000000UL_B5.elf
/c/avr-gcc/7.3.0-atmel3.6.1-arduino7/bin/avr-objcopy -j .text -j .data -j .version --set-section-flags .version=alloc,load -O ihex bootloaders/atmega328pb/24000000UL/optiboot_flash_atmega328pb_UART0_115200_24000000UL_B5.elf bootloaders/atmega328pb/24000000UL/optiboot_flash_atmega328pb_UART0_115200_24000000UL_B5.hex
\nOutput file name: bootloaders/atmega328pb/24000000UL/optiboot_flash_atmega328pb_UART0_115200_24000000UL_B5.hex

[rickygai]

here I attached two .hex zipped files for references:

Minicore Pre-built:
optiboot_flash_atmega328pb_UART0_115200_24000000L_B5.master.zip

My custom built:
optiboot_flash_atmega328pb_UART0_115200_24000000UL_B5.zip

[MCUdude]

MiniCore doesn't use Optiboot anymore. You should try Urboot instead. If you use the bootloaders already bundled with MiniCore you get automatic baud rate detection, which means that it doesn't matter which clock speed the AVR is running at. The bootloader will automatically adopt.

Also, the ATmega328PB is not certified to reliably work at 24 MHz. If they were, it would have been stated in the datasheet.

The issues you're seeing may be because that particular chip doesn't work well at 24 MHz, or because your hardware setup is flaky. I recommend you use a more modern bootloader and keep your setup within spec.